Tuesday, May 20, 2014

Everyone loves glowing sperm, right?

Doubly-labelled sperm from Price et al. Nature 400:449-452

Posted by Jessica Abbott on behalf of Katrine Lund-Hansen

Since next week's lab meeting might be the last before summer and field season, I have chosen a paper that should be of interest to all of us. Drosophila, sexual selection, speciation, and glowing sperm.

Abstract:
Background: Identifying traits that reproductively isolate species, and the selective forces underlying their divergence, is a central goal of evolutionary biology and speciation research. There is growing recognition that postcopulatory sexual selection, which can drive rapid diversification of interacting ejaculate and female reproductive tract traits that mediate sperm competition, may be an engine of speciation. Conspecific
sperm precedence (CSP) is a taxonomically widespread form of reproductive isolation, but the selective causes and divergent
traits responsible for CSP are poorly understood.
Results: To test the hypothesis that postcopulatory sexual selection can generate reproductive isolation, we expressed GFP or RFP in sperm heads of recently diverged sister species, Drosophila simulans and D. mauritiana, to enable detailed resolution of species-specific sperm precedence mechanisms. Between-species divergence in sperm competition traits and mechanisms prompted six a priori predictions regarding mechanisms of CSP and degree of cross asymmetry in reproductive isolation. We resolved four distinct mechanisms of CSP that were highly consistent with predictions. These comprise interactions between multiple sex-specific traits, including two independent mechanisms by which females exert sophisticated control over sperm fate to favour the conspecific male.
Conclusions: Our results confirm that reproductive isolation can quickly arise from diversifying (allopatric) postcopulatory sexual selection. This experimental approach to ‘‘speciation phenotypes’’ illustrates how knowledge of sperm precedence mechanisms can be used to predict the mechanisms and extent of reproductive isolation between populations and species.

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About us

We are a group of evolutionary biologists consisting of three PI:s (Jessica Abbott, Erik Svensson and Tobias Uller), and several postdocs, PhD-students and Master's students. We focus on ecology and phenotypic evolution, and topics as sexual selection and sexual conflict, epigenetic effects, frequency-dependent selection, and speciation processes in natural populations.

Research approaches include experimental evolution, quantitative genetics, experimental field studies of natural and sexual selection, and phylogenetic comparative methods. Our main study organisms are mainly invertebrates (insects, isopods, flatworms), although we also study lizards and birds.